Combustion apparatus



Nov. 5, 1935. F. A. CHAMBERS ET Al.

COMBUSTION APPARATUS Filed 001'.. 2, 1951 im i Patented Nov. 5, 1935 UNHTED STATES COMIBUSTION APPARATUS Frank A. Chambers and Charles F. McGinley.

Chicago, Ill.

Application October 2, 19317', Serial No. 566,526

2 Claims.

The invention relates to devices for producing efcient combustion of the fuel in boilers and for abating smoke.

One object of the invention is to provide improved' and efficient .means for producing subatV stant-ially complete combustion of the fuel in boilers which is adapted for use in different types of boilers.

Another object of the invention is to provide improved means for delivering hot air and steam into the rebox in such a manner as to cause substantially complete combustion of the fuel.

Another object of the invention is to provide improved means for delivering hot air and steam into the rebox which can be .easily installed in existing boilersI of different types.

Another object of the invention is to provide improved means, for delivering air and steam into` the firebox of the boiler to cause substantially complete combustion of the fuel, in which the mixing head with a steam nozzle and induction port is adjustable to produce the maximum eliciency with the minimum steam supply K under varying conditions.

Another object of the invention is to provide improved means for delivering air and steam into the firebox in which the steamjet is disposed in an elbow of an air pipe to muiile the noise produced by the steam and the induced air.

Other objects will appear from the description.

The invention consists in the several novel features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawingyliig. l is a longitudinal section of a boiler embodying the invention. Fig. 2 is a front elevation of the boiler. Fig. 3 is a section of the induction and mixing device. Figs.

' 4 and 5I are side elevations of thek elbow containing the mixing head.

The invention is applied to a return tube boiler I0 which may be of any suitable or usual construction and comprises a rebox I'I over a grateA I2. A coil of pipe I3 extends transversely across the chamber under the boiler in back of the preheatedair passing .to the induction devices It hereinafter described, which deliver steam and air to the combustion chamber over the fire-bed. One end I4 of this coil outside of the furnace is open to admit air to the coil. The other end is connected to a pipe I5 which extends across the front of the-furnace to deliver heated air to the mixing and induction devices t5.

Any desired number of induction devices may be used, and they are similar in construction.

Each of said devices comprises an elbow having a branch I'I which is connected to a branch l5:L of the pipe I5 so heated air can be drawn into the elbow. The other branch I9 of the elbow is connected to a pipe 2U which extends through 5 the front wall of the furnace to deliver a mixture of hot air and steam into the rebox above the grate to burn the volatile matter in suspension. A pipe 22, which is connected to recei-ve steam from the boiler, extends into the 10 elbow coaxially with the discharge branch I9, and supports a mixing head or member 2l This head is screw-threaded to the inner end of pipe 22 and is supported thereby in the elbow. A nozzle 24, with a small port 25 to discharge steam in the form of a small jet, is secured in a wall 2|'a forming the end of the head 2| which is adjacent the inner end of pipe 22. The inner end of the head 2l is hollow to form a mixing chamber 2s coaxial with the discharge-branch la of 20 the elbow. The nozzle 265 is disposed at the inner end of the chamber 26 and the outer end of this chamber is open to direct the fluid through the discharge branch and into pipe 2B. An oblique port 21 leads from the outside of the outer portion of the head to the inner end of the mixingrchamber 26 and adjacent the nozzle 24. A conical spreader 28, coaxial with the duct 25 in the nozzle 24, is secured in a member 3% which has a reversely cone-shaped inner end 3 I. Member 3E! is connected toand supported in the head by ribs 32. The portion 3S of the discharge. branch ofthe elbow is conoidal or constricted. The head 2i is smaller than the discharge branch I9 of the elbow to provide an annular space or 35 passage IS)a around the head and through which heated air will be drawn by the stream of mixed air and steam discharged under pressurefrom the mixing chamber 26 in the head. This exemplifes a device in which there is a double induetion of heated air to the stream, heated air being first drawn into the mixing chamber 2G through port 2l where the air and steam are impinged against spreader 28; so they will be mixed, and the discharge of the mixed air and steam from the open end of chamber 26, which serves, in effect, as a nozzle, draws air through passage I!!a to mix an additional volume of heated air to the mixture from the head Z, so that sufficient oxygen will be delivered to the rebox for complete combustion of the fuel. By adjusting the head longitudinally within the restricted or conoidal portion 33 of the discharge branch of the elbow, the effective area of the air induction space between the head and the elbow can be varied to regulate the volume of air to meet varying conditions in furnaces or in furnaces of different types. A set screw 34 is threaded to a boss 35 on the elbow through which pipe 22 is slidable and is adapted to lock the pipe to hold the head in its desired or adjusted position in the discharge branch I9 of the elbow. For convenience in mounting and removal of the mixing elbow, branch Il of the elbow is split as at 36 and provided with lugs 3l for a bolt 38 which is adapted to clamp the elbow around one end of pipe l5a. The other branch of the elbow is provided with similar clamping means for pipe 20.

To obtain practically perfect combustion of coal, black smoke is usually caused by insufiicient air in the furnace. Air is brought in through the grates. The oxygen in the air combines with the carbon from the coal in the approximate proportion of two parts of oxygen to one part of carbon. So long as the supply of air is sufficient and well distributed to obtain a proper mixture, a fairly smokeless fire is the result. When this is prevented by too much coal over the grate, there will be incomplete combustion with a resultant dull fire and the emission of black smoke. To produce practically perfect combustion, it is necessary, not only to burn the carbon in the coal, but also the volatile gases. The various proportions of the constituents of coal vary widely as to its fuel value in coal derived from different seams from different sections of the country. To achieve practically perfect combustion, it is necessary to burn the fuel and gases in the furnace. The combustion resulting from air entering the bottom of the fuel bed forms carbon dioxide from the chemical combination of the carbon of the coal and the oxygen of the air. rI'he decomposition of the carbon dioxide to carbon monoxide results as the former is brought into contact with more incandescent carbon and the combustion of the volatile matter to form the various hydrocarbon gases. The recombination of the carbon monoxide with excess oxygen at the top of the fire again forms Vcarbon dioxide and completes the combustion of the volatile matter. To obtain substantially perfect combustion, the temperature of the furnace must be kept sufficiently high to give quick combustion, the flame must have enough time in the air, so that combustion can be completed before it reaches the boiler tubes, and the air, and gas should be thoroughly mixed for complete combustion, which usually occurs in the rebox of .the furnace.

In practice it has been found that practically perfect combustion may be obtained and smoke prevented when the volatile gases and separated free carbon are brought into intimate contact with the proper quantity of air and maintained at a temperature above the ignition point until oxidation is complete before they are brought into contact with the heat absorbing surfaces of the boiler. Mere excess of air will not effect smokeless combustion, -even if the gases and air 'are thoroughly mixed, if the temperature is prematurely reduced below that necessary for combustion by contact with the heat absorbing surfaces of the boiler. Y

In operation, the steam discharged from the Anozzle 24 into the mixing chamber 2B will draw heated air through the heating coil I3 and pipe I5 into the elbow. A portion of the hot air will be drawn into the mixing chamber 25 through port 2l, and in said chamber it will be intimately `mixed with the steam, the spreader 28 acting as a baffle to assist in the mixing. The stream of mixed steam and air discharged from the mixing chamber into the discharge branch I9 of the elbow will draw air through the annular passage I!!al around the head. After the second in- 5 duction of heated air, the mixture will pass from the elbow into pipe 29 and to the flrebox. The volume of air added to the stream on the second -induction may be varied to adaptthe device for different conditions by adjustment of the head to and from the constricted portion 3-3 of the elbow. The latter acts as an induction nozzle. Pipe 22 can be adjusted from the outside of the elbow to shift head 2l to and from the constricted portion 33. This makes it possible to deliver the necessary volume of hot air and steam to the rebox to produce substantially perfect combustion. The integral clamps at the ends of the branches of the elbow make it possible to quickly install and remove the device whenever necessary. While the invention has been illustrated with a return flue boiler, it is adapted for use with boilers of any of the different well-known types. p

The invention exemplifies devices by which a mixture of hot air and steam, in proper quantity and maintained at a temperature above the ignition point, is brought into intimate contact with the volatile gases and separated free carbon to complete oxidation thereof before they are brought into contact with the heat-absorbing surfaces of the boiler; in which a suiiicient amount of air for perfect combustion of the volatile gases is delivered to the rebox to produce the aggregate mixture of air and combustible at a temperature which is sufticiently high to complete oxidation of the volatile combustible. The invention also exemplifies a device in which there is an initial induction of hot air to the steam from the jet and a. second induction of hot 40 air to the mixed steam and hot air, which is simple in construction, and efcient in operation; also a device in which the nozzle is adjustable relatively to the constricted discharge of the elbow to vary the suction to meet the re- 451-.--

quirements of different furnaces; also a con? struction in whichA the mixing occurs in an elbow which mufiies the noise produced by the jet.

The invention is not to be understood as restricted to the details set forth, since these may 50 l claim as new and desire'to secure by Letters 551: A

Patent, is:

1. As a new article of manufacture, a device for delivering hot air and steam into the rebox of a heating apparatus for increasing combustion and abating smoke, comprising an elbow having an inlet branch for receiving hot air and a branch extending substantially at right angles to the inlet branch and adapted to discharge into the rebox, an elongated head disposed in the bent portion of the elbow and arranged so that it is axially aligned with, and one end thereof extends into, the discharge branch of said elbow, a nozzle in the central portion of the head, and a pipe for delivering steam to the nozzle extending through the bent portion of the elbow and connected to the other end of the head, said head being provided at said one end thereof with a mixing chamber into which the nozzle discharges and with a discharge opening for the chamber aligned with and facing in the u' direction of the discharge branch of the elbow, said head also being provided with an angular induction port in the side portion adjacent to the inlet branch for admitting hot air to the chamber for admixture with the steam from the nozzle and having said one end thereof spaced from the side wall of the discharge branch of the elbow to forman air passage around the head through which hot air will be drawn into mixed relation with the mixed air and steam emanating from the mixing chamber via the discharge opening.

2. As a new article of manufacture, a device for delivering hot air and steam into the rebox of a heating apparatus for increasing combustion and abating smoke, comprising an elbow having an inlet branch for receiving heated air and a branch at substantially right angles to the inlet branch adapted to discharge into the firebox provided with a tapered outer end, an elongated head disposed in the bent portion of the elbow and arranged so that it is axially aligned with, and one end thereof extends into, the discharge branch of said elbow, a nozzle in the central portion of the head, a pipe for delivering steam to the nozzle extending through an opening in the bent portion of the elbow and connected to the other end of the head, said head being provided at said one end thereof with a mixing chamber into which the nozzle discharges and with a discharge opening for the chamber aligned with and facing in the direction of the discharge branch of the elbow, said head also being provided With an angular induction port in the side portion adjacent to the inlet branch for admitting hot air to the chamber for admixture with the steam from the nozzle and having said one end thereof spaced from the side wall of the discharge branch of the elbow to form an air passage around the head through which hot air will be drawn into mixed relation with the mixed air and steam emanating from the mixing chamber via the discharge opening, and means associated with the part of the bent portion of the elbow having the opening through which the pipe extends for supporting the pipe so that it is slidable axially of the discharge branch of the elbow in order to vary the position of the head with respect to the tapered outer end of the discharge branch and thus regulate the size of the air passage around the head.

FRANK A. CHAMBERS. CHARLES F. MCGINLEY. 

